scholarly journals Setting the tree-ring record straight

2020 ◽  
Author(s):  
Josef Ludescher ◽  
Armin Bunde ◽  
Ulf Büntgen ◽  
Hans Joachim Schellnhuber
Keyword(s):  
Tree Ring ◽  
Temperature Reconstruction ◽  
Climate Impacts ◽  
Model Data ◽  
Mathematical Transformation ◽  
Harvest Dates ◽  
Temperature Reconstructions ◽  
Historical Temperature ◽  
Historical Model

<p>Tree-ring chronologies are the main source for annually resolved and absolutely dated temperature reconstructions of the last millennia and thus for studying the intriguing problem of climate impacts. Here we focus on central Europe and compare the tree-ring based temperature reconstruction with reconstructions from harvest dates, long meteorological measurements, and historical model data. We find that all data are long term persistent, but in the tree-ring based reconstruction the strength of the persistence quantified by the Hurst exponent is remarkably larger (h = 1.02) than in the other data (h = 0.52 − 0.69), indicating an unrealistic exaggeration of the historical temperature variations. We show how to correct the tree-ring based reconstruction by a mathematical transformation that adjusts the persistence and leads to reduced amplitudes of the warm and cold periods. The new transformed record agrees well with both the observational data and the harvest dates-based reconstructions and allows more realistic studies of climate impacts. It confirms that the present warming is unprecedented.</p>

scholarly journals Setting the tree-ring record straight

2020 ◽  
Vol 55 (11-12) ◽  
pp. 3017-3024
Author(s):  
Josef Ludescher ◽  
Armin Bunde ◽  
Ulf Büntgen ◽  
Hans Joachim Schellnhuber
Keyword(s):  
Tree Ring ◽  
Temperature Reconstruction ◽  
Climate Impacts ◽  
Model Data ◽  
Mathematical Transformation ◽  
Harvest Dates ◽  
Temperature Reconstructions ◽  
Historical Temperature ◽  
Historical Model

Abstract Tree-ring chronologies are the main source for annually resolved and absolutely dated temperature reconstructions of the last millennia and thus for studying the intriguing problem of climate impacts. Here we focus on central Europe and compare the tree-ring based temperature reconstruction with reconstructions from harvest dates, long meteorological measurements, and historical model data. We find that all data are long-term persistent, but in the tree-ring based reconstruction the strength of the persistence quantified by the Hurst exponent is remarkably larger ($$h\cong 1.02$$ h ≅ 1.02 ) than in the other data ($$h=$$ h = 0.52–0.69), indicating an unrealistic exaggeration of the historical temperature variations.We show how to correct the tree-ring based reconstruction by a mathematical transformation that adjusts the persistence and leads to reduced amplitudes of the warm and cold periods. The new transformed record agrees well with both the observational data and the harvest dates-based reconstructions and allows more realistic studies of climate impacts. It confirms that the present warming is unprecedented.

The significance of climate and solar variability on historical European grain prices

2020 ◽  
Author(s):  
Fredrik Charpentier Ljungqvist ◽  
Peter Thejll ◽  
Bo Christiansen ◽  
Andrea Seim ◽  
Claudia Hartl ◽  
...  
Keyword(s):  
Early Modern ◽  
Tree Ring ◽  
Early Modern Europe ◽  
Solar Forcing ◽  
Time And Space ◽  
Climate Signal ◽  
Temperature Reconstructions ◽  
Modern Europe ◽  
Grain Prices

<p>Grain was the most important food source for a majority of the population in early modern Europe (<em>c</em>. 1500–1800). The price level and volatility had huge societal effects: high prices tended to increase mortality, decrease fertility as well as affect overall consumption patterns. To what extent climate variability influenced the long-term grain price evolution in early modern Europe has for a long time been a matter of debate. Recent advances in high-resolution palaeoclimatology and historical climatology have made it possible to reassess the grain price–climate relationship in time and space with unprecedented detail (Esper <em>et al</em>. 2017). We analyse the climate signal in 56 multi-centennial long series of annual prices of barley, oat, rye, and wheat across Europe. The grain price–climate relationship in regional clusters of grain price data is analysed using both tree-ring based temperature reconstructions, documentary-based temperature reconstructions, tree-ring based drought reconstructions, and early temperature and precipitation instrumental data, considering possible different climate responses in each grain type and different seasonal targets. In addition, we systematically investigate whether, and to what extent, the imprints of variations in solar forcing, including possible lag effects, can be detected in the grain prices.</p><p>We find a highly significant and persistent negative temperature–price relationship (i.e., cold = high prices and vice versa) across all of Europe and for all four grain types using both temperature reconstructions and instrumental temperature data. Excluding the Thirty Years’ War (1618–1648) and the period following the French Revolution (1789), this relationship is as strong as <em>r</em> = –0.41 between the annual average of all the 56 included European grain price series and the reconstructed June–August temperature for the previous year. The correlations to drought and precipitation are, on the other hand, mainly insignificant and inconsistent in time and space. The evidence for the existence of the effect of solar forcing variations on early modern European grain prices is not strong, although we can detect statistically significant grain price–solar forcing relationships for certain regions. In conclusion, we find much stronger evidence than hitherto reported for long-term temperature imprints on historical grain prices in Europe, implying that temperature variability and change have been a more important factor in European economic history, even in southern Europe, than commonly acknowledged.</p><p> </p><p><strong>Reference:</strong></p><p>Esper J., <em>et al</em>., 2017. Environmental drivers of historical grain price variations in Europe. <em>Clim. Res</em>. 72: 39–52.</p>

scholarly journals A 368-year maximum temperature reconstruction based on tree ring data in northwest Sichuan Plateau (NWSP), China

2016 ◽  
Author(s):  
Liangjun Zhu ◽  
Yuandong Zhang ◽  
Zongshan Li ◽  
Binde Guo ◽  
Xiaochun Wang
Keyword(s):  
Tree Ring ◽  
Land Surface ◽  
Temperature Reconstruction ◽  
Temperature Variability ◽  
Maximum Temperature ◽  
Spatial Correlations ◽  
Calibration Period ◽  
Tree Ring Data ◽  
Temperature Reconstructions ◽  
The Mean

Abstract. We present a reconstruction of July–August mean maximum temperature variability for northern West Sichuan Plateau (NWSP), China based on a chronology of tree-ring widths over the period 1646–2013 AD. A regression model explains 37.1 % of the variance of July–August mean maximum temperature during the calibration period from 1954 to 2012. Seven major cold periods were identified including 1708–1711, 1765–1769, 1818–1821, 1824–1828, 1832–1836, 1839–1842 and 1869–1877, and three major warm periods occurred between 1655–1668, 1719–1730 and 1858–1859 in our reconstruction. Comparison with other nearby temperature reconstructions and spatial correlations with gridded land surface temperature dates revealed that our temperature reconstruction has high spatial representativeness. 20th century rapid warming wasn’t obvious in the NWSP mean maximum temperature reconstruction, which implied that mean maximum temperature might play an important and different role in global change as unique temperature indicators. Multi-taper method (MTM) spectral analysis revealed significant periodicities of 170-, 49–114-, 25–32-, 5.7-, 4.6–4.7-, 3.0–3.1-, 2.5- and 2.1–2.3-year quasi-cycles at a 95 % confidence level. The mean maxi mum temperature variability in northwest Sichuan may be affected by ENSO, PDO, AMO and solar activity.

scholarly journals Tree-ring responses to extreme climate events as benchmarks for terrestrial dynamic vegetation models

2014 ◽  
Vol 11 (2) ◽  
pp. 2537-2568 ◽  
Author(s):  
A. Rammig ◽  
M. Wiedermann ◽  
J. F. Donges ◽  
F. Babst ◽  
W. von Bloh ◽  
...  
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Extreme Events ◽  
Ring Width ◽  
Climate Extremes ◽  
Tree Ring Width ◽  
Model Data ◽  
Vegetation Models ◽  
The Impact

Abstract. Climate extremes can trigger exceptional responses in terrestrial ecosystems, for instance by altering growth or mortality rates. Effects of this kind are often manifested in reductions of the local net primary production (NPP). Investigating a set of European long-term data on annual radial tree growth confirms this pattern: we find that 53% of tree ring width (TRW) indices are below one standard deviation, and up to 16% of the TRW values are below two standard deviations in years with extremely high temperatures and low precipitation. Based on these findings we investigate if climate driven patterns in long-term tree growth data may serve as benchmarks for state-of-the-art dynamic vegetation models such as LPJmL. The model simulates NPP but not explicitly the radial tree ring growth, hence requiring a generic method to ensure an objective comparison. Here we propose an analysis scheme that quantifies the coincidence rate of climate extremes with some biotic responses (here TRW or simulated NPP). We find that the reduction in tree-ring width during drought extremes is lower than the corresponding reduction of simulated NPP. We identify ten extreme years during the 20th century in which both, model and measurements indicate high coincidence rates across Europe. However, we detect substantial regional differences in simulated and observed responses to extreme events. One explanation for this discrepancy could be that the tree-ring data have preferentially been sampled at more climatically stressed sites. The model-data difference is amplified by the fact that dynamic vegetation models are designed to simulate mean ecosystem responses at landscape or regional scale. However, we find that both model-data and measurements display carry-over effects from the previous year. We conclude that using radial tree growth is a good basis for generic model-benchmarks if the data are analyzed by scale-free measures such as coincidence analysis. Our study shows strong reductions in carbon sequestration during extreme years. However, for a better understanding of the impact of extreme events on e.g. the long-term fate of the European carbon balance, more long-term measurement data and improved process-based models are needed.

scholarly journals Overcoming model instability in tree-ring-based temperature reconstructions using a multi-species method: A case study from the Changbai Mountains, northeastern China

2021 ◽  
Author(s):  
Liangjun Zhu ◽  
Shuguang Liu ◽  
Haifeng Zhu ◽  
David J. Cooper ◽  
Danyang Yuan ◽  
...  
Keyword(s):  
Tree Ring ◽  
Tree Species ◽  
Minimum Temperature ◽  
Northeast China ◽  
Growing Season ◽  
Single Species ◽  
Temperature Reconstruction ◽  
Atlantic Multidecadal Oscillation ◽  
Changbai Mountains ◽  
Temperature Reconstructions

Abstract. The unstable sensitivity of growth-climate relationships greatly restricts tree-ring-based paleoclimate reconstructions, especially in areas with frequent divergence problems, such as the temperate zone in northeast China. Here, we propose an original tree-species mixing method to overcome this obstacle and improve the stability and reliability of reconstruction models. We take the tree-ring based growing-season minimum temperature reconstruction for the northern Changbai Mountains in northeast China as an example to illustrate the method. Compared with previous temperature reconstruction models, our reconstruction model is more stable and reliable and explains up to 68 % of the variance. It is also highly consistent with historical records and tree-ring-based temperature reconstructions from the nearby Xiaoxing'an Mountains and from across the Northern Hemisphere. Our reconstruction uses two different tree species and is more accurate than temperature reconstructions developed from a single species. Over the past 259 years (AD 1757–2015), five significant cold periods and five warm periods were identified. The reconstruction indicates rapid warming since the 1980s, which is consistent with other instrumental and reconstructed records. We also found the Atlantic Multidecadal Oscillation plays a crucial role in driving the growing-season minimum temperature in the northern Changbai Mountains.

scholarly journals Temperaturvariationen und Jahrringe | Temperature variation and tree rings

2004 ◽  
Vol 155 (6) ◽  
pp. 213-221 ◽  
Author(s):  
Jan Esper ◽  
Kerstin Treydte ◽  
David C. Frank ◽  
Holger Gärtner ◽  
Ulf Büntgen
Keyword(s):  
Temperature Variation ◽  
Tree Ring ◽  
Tree Rings ◽  
Large Scale ◽  
Temperature Trends ◽  
Temperature Reconstructions ◽  
Climatic Signals

The paper reviews some of the current objectives, concepts and results of dendroclimatic research focusing on long-term temperature trends and large-scale, tree-ring based temperature reconstructions. We discuss the significance of single treering parameters, their qualities and limitations, and address the issue of emphasizing climatic signals in long series of tree-ring records. We conclude with a discussion of current challenges faced by dendroclimatological research.

scholarly journals Testing long-term summer temperature reconstruction based on maximum density chronologies obtained by reanalysis of tree-ring datasets from northernmost Sweden and Finland

2013 ◽  
Vol 9 (5) ◽  
pp. 5659-5700
Author(s):  
V. V. Matskovsky ◽  
S. Helama
Keyword(s):  
Tree Ring ◽  
Low Frequency ◽  
Temperature Reconstruction ◽  
Summer Temperature ◽  
Temperature History ◽  
Maximum Latewood Density ◽  
Northern Fennoscandia ◽  
Latewood Density ◽  
Novel Method

Abstract. Here we analysed the maximum latewood density (MXD) chronologies of two published tree-ring datasets: from Torneträsk region in northernmost Sweden (TORN, Melvin et al., 2013) and from northern Fennoscandia (FENN, Esper et al., 2012). We paid particular attention to the MXD low-frequency variations to reconstruct long-term summer (June–August, JJA) temperature history. We used published methods of tree-ring standardization: regional curve (RC) standardization, combined with signal-free (SF) implementation. Comparisons with a single-RC (RC1) and multiple-RC (RC2) were also carried out. We develop a novel method of standardization, the correction (C) implementation to SF (hence, RC1SFC or RC2SFC), tailored for detection of pure low-frequency signal in tree-ring chronologies. In this method, the error in RC1SF (or RC2SF) chronology, is analytically assessed and extracted to produce a RC1SFC or RC2SFC chronology. In TORN, the RC1SF chronology shows higher correlation with summer temperature (JJA) than RC1SFC, whereas in FENN the temperature signals of RC1SF chronology is improved by correction implementation (RC1SFC). The highest correlation between differently standardized chronologies for two datasets is obtained using FENN-RC2SFC and TORN-RC1 chronologies. Focusing on lowest frequencies, the importance of correction becomes obvious as the chronologies become progressively more correlative with RC1SFC and RC2SFC implementations. Subsampling the FENN data (which presents a higher number of samples than TORN dataset) to the chronology sample size of TORN data shows that the chronologies consistently bifurcate during the 7th, 9th, 17th and 20th centuries. We used the two MXD datasets to reconstruct summer temperature variations over the period −48–2010 calendar years. Our new reconstruction shows multi-decadal to multi-centennial variability with changes in the amplitude of the summer temperature of 2.6 °C in average during the Common Era.

scholarly journals Climate Mobility and Development Cooperation

2021 ◽  
Author(s):  
Robert Stojanov ◽  
Sarah Rosengaertner ◽  
Alex de Sherbinin ◽  
Raphael Nawrotzki
Keyword(s):  
Climate Adaptation ◽  
Human Mobility ◽  
Climate Impacts ◽  
Development Cooperation ◽  
Climate Variability And Change ◽  
Policy Frameworks ◽  
And Migration ◽  
And Function ◽  
Role And Function

AbstractDevelopment cooperation actors have been addressing climate change as a cross-cutting issue and investing in climate adaptation projects since the early 2000s. More recently, as concern has risen about the potential impacts of climate variability and change on human mobility, development cooperation actors have begun to design projects that intentionally address the drivers of migration, including climate impacts on livelihoods. However, to date, we know little about the development cooperation’s role and function in responding to climate related mobility and migration. As such, the main aim of this paper is to outline the policy frameworks and approaches shaping development cooperation actors’ engagement and to identify areas for further exploration and investment. First, we frame the concept of climate mobility and migration and discuss some applicable policy frameworks that govern the issue from various perspectives; secondly, we review the toolbox of approaches that development cooperation actors bring to climate mobility; and third, we discuss the implications of the current Covid-19 pandemic and identify avenues for the way forward. We conclude that ensuring safe and orderly mobility and the decent reception and long-term inclusion of migrants and displaced persons under conditions of more severe climate hazards, and in the context of rising nationalism and xenophobia, poses significant challenges. Integrated approaches across multiple policy sectors and levels of governance are needed. In addition to resources, development cooperation actors can bring data to help empower the most affected communities and regions and leverage their convening power to foster more coordinated approaches within and across countries.

scholarly journals Analysis of long-term temperature monitoring of multiple wind turbines

2021 ◽  
pp. 002029402110130
Author(s):  
Xian Wang ◽  
Qian-cheng Zhao ◽  
Xue-bing Yang ◽  
Bing Zeng
Keyword(s):  
Wind Turbines ◽  
Temperature Rise ◽  
Performance Optimization ◽  
Wind Farm ◽  
Engineering Practice ◽  
Multiple Perspectives ◽  
Temperature State ◽  
Condition Monitoring Systems ◽  
Historical Temperature

The historical temperature data logged in the supervisory control and data acquisition (SCADA) system contains a wealth of information that can assist with the performance optimization of wind turbines (WTs). However, mining and using these long-term data is difficult and time-consuming due to their complexity, volume, etc. In this study, we tracked and analyzed the 5-year trends of major SCADA temperature rise variables in relation to the active power of four WTs in a real wind farm. To uncover useful information, an extended version of the bins method, which calculates the standard deviation (SD) as well as the average, is proposed and adopted. The implications of the analysis for engineering practice are discussed from multiple perspectives. The research results demonstrate a change in the patterns of the main temperature rise variables in a real wind farm, completeness of the monitoring of the WT internal temperature state, influence of wind turbine aging on temperature signals, a correlation between different measurement points, and a correlation between signals from different years. The knowledge gained from this research provides a reference for the development of more practical and comprehensive condition monitoring systems and methods, as well as better operation maintenance strategies.

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